Fuse



April 1951 V R. L. GRAUMANN ETAL 2,546,999

FUSE

Original Filed July 1, 1942 43 62 FIG. 29 4/ 45 FIG. 2. Q

4/ 3 INVENTORS RAYMOND L. GRAUMA/V/V W/LL/AM J DO/VAHUE, JR.

ATTORNEY Patented Apr. 3, 1951 FUSE Raymond L. Graumann, Alexandria,Va., and William J Donahue, Jr., Washington, D. 0.

Original application July 1, 1942, Serial No.

449,324. Divided and this application December 2'7, 1946, Serial No. 718,729

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 1 2 Claims.

This invention relates to improvements in fuzes for explosive projectiles, and the instant disclosure thereof is a division of an application for United States patent on Fuzes, filed by Raymond L. Graumann and William J. Donahue, Jr., July 1, 1942, Serial No. 449,324, now Patent No. 2,427,671.

A nose fuze such as the instant device is, comprises an explosive-loaded instrument for igniting or detonating the explosive filler of the projectile which carries it. Said fuze is of the pointdetonating type and it is intended to function by igniting the burster charge or explosive filler on impact with the target. Because of the sensitivity of the elements of the explosive train in the nose fuze, it is necessary to embody adequate safety features in order to forestall serious accidents during the transportation of projectiles, loading ammunition on board ships, loading projectiles into guns nd, especially, while the projectile is subjected to the sudden and violent forces of being fired from the gun.

The safety features incorporated in the instant fuze render it both bore safe and detonator safe. That is to say, the fuze is immune to becoming armed in case the projectile encounters an obstruction in the bore of the gun, hence will not cause a bore detonation. It is detonator safe because its construction is such that should the detonator be set off for any reason while the fuze is in the unarmed condition, the booster charge of the fuze, hence the explosive filler, will not be detonated.

These safety features are obtained by maintaining a break in the continuity of the explosive train of the fuze until the projectile actually begins its flight from the muzzle of the gun. Thereupon the centrifugal force developed by the spinning of the projectile becomes effective to establish the continuity of the explosive train, in other words to arm the fuze, in readiness for the firing thereof when the projectile strikes the target.

Therefore, one of the objects of the invention is to provide a nose fuze which is contrived to insure the deferment of registration of the components of the explosive train with the firing pin or its equivalent, until the projectile is subjected to centrifugal forces such as will ordinarily be developed therein only upon firing said projectile from a gun.

Another object of the invention is to provide a fuze of the type known as supersensitive, that is to say, a fuze which is sufficiently delicate in its response to insure its functioning upon striking the lightest and most fragile targets, for example, the fabric of an airplane.

Another object of the invention is to provide a fuzewith a comparatively fragile nose, which fragility insures its ready yielding or collapse when striking a target offering appreciable resistance to penetration.

A further object of the invention is to provide a nose fuze which is characterized by a yoke spring which arrests the firing pin until the instant of impact with the target, said yoke spring initially abutting a shoulder to accomplish that purpose, and then during flight when spread out of contact with the shoulder by the centrifugal action of the rotor detents, persisting in said function of arresting the firing pin by the friction factor between the yoke spring and fuze cover.

Other objects and advantages will appear in the following specification, reference being had to the accompanying drawing in which: M

Fig. 1 is a longitudinal section of the nose fuze, showing the parts in the static position assumed prior to flight;

Fig. 2 is a horizontal section of the nose fuze, taken substantially on the line 2-2 of Fig. 1, and

Fig. 3 is a view similar to Fig. 1, illustrating the fuze in the firing position, parts being shown in elevation.

In carrying out the invention provision is made of a fuze 25 which has a body 26 with a base 2! at the aft end. The base 27 is externally threaded at 28 for screwing into the nose of an explosive projectile. The body 26 includes a boss 29 at the forward end, the base and boss comprising a single metal piece which has the following characteristics.

A cavity 30 in the base 21 contains the booster charge 3|, the latter being held in place by a closure 32 and a marginal crimp 33. A bore contains a lead-in 35, usually composed of the same substance as the entire explosive train, namely Tetryl. As seen in the drawings, the

bore 34 communicates at its aft and forward ends respectivelywith the cavity 30 and with a chamber 36. Said chamber comprises a kerf which is cut in from the point of the fuze boss 29. The forward part of it takes in the entire ogive as seen in Fig. 2, ending at walls 31 which can be identified as extensions. From there on back the chamber has a semi-circular contour 38, the axis 39 thereof being set back a little way from the common face of the walls 3'! so as to delineate two flat terminals 40. These terminals join the Walls 31, are tangential to the contour 38 are parallel to each other.

and, usually,

V Ihe chamber 38 also has plane Walls M (Fig. 1). These confront each other, and extend forwardly and outwardly to complete the identity of the kerf mentioned at the beginning. The circular part of the chamber 36 forms an adequ i for the detonator-carrier or rotor, presently described in detail, and the rotor may freely do such turning in the chamber as will be required of it in the flight of the projectile and fuze.

A circular hole 42 is bored 1 from the point o f the boss 29, intersecting the kerf of hechamber 36. Said hole constitutes a yield-opening into which the circular pad of the firingpi-n recedes under point-pressure The axis of the chamber 36 is perpendicular to the axis of the fuzc and is at right angles thereto. Alined bores M intersect the chamber 35 in an off-center position with reference to the rotor, the -outer-an d backparts thereof at 46% functioning as shoulders. The bores emerge at the exterior of the ogive where the surface of theboss 29 is slotted across the boreson opposite of the boss 29 to provide passageways l-E. which start at the-point and extend back almost to a circular wall 36 nearwhichthe thread course fitends.

The passageways s intersect the. outer ends of the bores 65, the latter thus dividing the passage ways into long and short components 6? and 48 which, 1'espectively,-.are occupied and occupiable by-the free endsof the yoke spring in the mannor presently explained. Acct-eris ultimately appliedto'the fuse boss tii, fitting the ogive veritightly and being spun ate!) behind the circular wallet to insure itsstaying inplaee. The for-- ward-end ofthe coverhas an opening 5 L which is delineated by an inturned rim of thecover. This rim-serves as a-stcp flange-for the circular pad of-the firing pin.

"Specific reference isnow made to parts previously mentioned but deferred as to description. The rotor 53 which is a circular-disk, has a turning vfit in the kerf 38 of semicircular contour. It has recesses 5 in its plane faces-on opposite sides. When these are occupied by the pin ends 55 of :the detents Bethe rotor is prevented from turning. Under thatcircumstance-the rotor is in its unarmed position, and the relationshipofthe recesses 55 to the cross-bore 5? in the rotor is such that the detonator-.58 contained by-the crossbore will be out of registrationwith'the-axis of the fuze, hence both bore safe and detonatorsafe.

Since the turning of 'the rotor cannot occur until-the projectile has left the'muzzle, there is no way in which the bursting charge could be ignited because the rotor remains locked in place as long as there is a lack of sufiicientcentrifugal force to displace the detents 56. Since the degree of centrifugal force required is not ac quired while the projectile is stilltraveling the barrel, it follows that the detonator will remain in its biased position (Fig. 2). The-fuze is thus rendered bore safe, and if by any chance the detonator 58 should be set off, the same biased position of the detonator would keep thefiash from the'rest of the explosive train, thus rendering the fuze detonator safe. The detents.,. 5(-3 are. in the form of cylindrical or otherwise cross sectionally formed plugs, the outer or butt ends of which are desirably rounded at .59 as shown. The rotor is lead-weighted at 53a to cause rotorturning; under centrifugal force to arm the-'fuze.

,I'heyoke spring 60 comprises a central, round plate 6| from opposite-sides of which the spring arms 62 diverge. The places where thearmsjoin 4 the plate comprise rounded heels 63 which have bearing against the contiguous parts of the cover 49. The bearing involves enough pressure from the cover to .keep the spring arms flexed inwardly toward the axis. of the fuze, down against the rounded butts or the detents and in line with the shoulders 44 for contact with which the arm fore exercisean axially centered thrust inwardly upon ,the 'detents, keeping them seated and centered truly in their bores 43 and upon the rotor. lp making the yoke spring 60 the arms 62 are given the U -shapeshown with reference to the plate -61, with an initial tendency to bear down Qn th e detents when slipped into place. Such inwardly directed tension as the arms have is augmented by the pressure of the cover 49 on the heels 63 when the final assembly is made. The arms 62 fit the passageways 65 loosely, and it is inthese passageways that the'arms flex outwardly bycentrifugal force impressed both on the de--- tentsand on the arms leading up to the assumption of the final position in Fig. 3. V

An. opening 65 in the center of the plate 61 contains the shank of the firing pin 66, apart of the shank being swaged over the plate. The pin projects from a base pad 557 against which the plate fil is held immovably by the swaging. The rim of the disk is adapted to ride the wall of the hole #212 asthe firing pin moves to the firing position. The disk 61 comprises part of the point seal of thefuze, its perimeter being rabbeted'at 68 to define-an annular seat for the rim 52 of the cover. The previously mentioned pressure of the cover on the heels 63 reacts to force the disk or pad alto its farthest forward position and into sealing engagement with the rim 52".

The operation of the fuze is readily understood. Figs. 1 and-Z-illustr'ate thedormant condition of the fuze, in other words, the condition of the parts after assembly'and upto the time of-firing. The .detonator' 58' assumes the biased position shown-in-Figk2jthat is, biased with-respect to-the-firing pin 66 and longitudinal axis of the fuze. It is-locked there by the pin ends-55 ofthe detents -56. The detents are held in thelocked positions and'in their bores :23 by the yoke spring GlL'the endsllfifofiwhich are braced-against-the shoulders 54.

;After cessation of the set-back force upon firing the projectile, centrifugal force causes the 'detents 56 to move outwardly, withdraws thepin ends '55 from the rotor recesses fi i and spreads the yoke spring outw ards against the cover ill; therebydisplacing the ends l f. from the shoul- (IBIS- 44. Sincethe rotor is now free to turn or arm, the weights- 53a line up across the fuze, moving-the detonator -53 into alinement :with the lead-in35, thus completing the explosive'train.

The firing pin 66 remains in its forward position -during the flight of'the projectila: due to friction between the rear tips of the ends 65 "of the yoke-springand cover. These'tipsare driven against the cover by the force of the centrifugally actuated 'detents55, and the pressure thereof is sufficiently great to prevent the premature inwarddisplacement of the firing pin pad- 6? due to air pressure. ;In striking the target, theflring pin ahd--the-yoke spring are driven rearwardly with reference to the fuze, then assuming t'lie position shown in Fig. 3. -The yoke spring is guided in the-long-slot component/sill, theshort components 48-pr'ovidingexterna1- reliefs orrecesses for theentry of theends '64 in the-final positionof the yoke spring. The stabbing of the detonator 58 by the firing pin initiates the explosive train.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

We claim: 7

1. In a fuze, a body having a kerf providing a chamber and having radial bores extending from the chamber, a portion of each bore forming a shoulder, a detonator-carrier turnably mounted in the chamber, detent means occupying the bores and holding the carrier in an initially unarmed position, a firing pin to explode the detonator, and a spring yoke carrying said firing pin, said yoke having arms superimposed upon the detent means to hold them in the bores and having tips engaging the shoulders to brace the yoke in position to hold the firing pin in the forward position.

2. In a fuze, a body having a detonator carrierchamber and having bores extending radially from the chamber, detonator carrier detent means radially movable in the bores, means to restrain the detent means consisting of a basepad, a yoke afiixed to the base pad and having spring arms with rounded heels formed by bends at which the spring arms extend away from the base pad toward and over the outer ends of the detent means, and a cover fitted on the body, bearing on the heels to flex the arms inwardly toward the axis of the fuze.

RAYMOND L. GRAUMANN.

WILLIAM J. DONAHUE, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

